Influence of Surface Modifications on Bacterial Adherence to Implant Abutment Materials.

The purpose of this study was to investigate the effects of various titanium and zirconia polishing protocols on the colonization of oral bacteria. Titanium and zirconia discs were divided into five groups: unpolished (control, UNP) and polished with Brownie only (BRO), Brownie plus Greenie (BPG), Brownie plus Greenie plus Supergreenie (BGS), and CeraMaster Coarse plus CeraMaster polishing tips (CER). The samples were sterilized and immersed in unstimulated saliva, then incubated in a liquid suspension of Streptococcus gordonii (S gordonii). The number of attached bacteria were counted 48 hours after the diluted suspensions were inoculated. Data were analyzed with ANOVA and Tukey test (P < .05). For titanium discs, the average number of bacteria from each group (CFU/mm2) was 1.51 x 103 for UNP; 3.71 x 103 for BRO; 5.65 x 103 for BPG; 8.99 x 102 for BGS; and 8.49 x 102 for CER. For zirconia, the averages were 2.87 x 102 for UNP; 3.16 x 102 for BRO; 3.50 x 102 for BPG; 1.83 x 102 for BGS; and 8.73 x 101 for CER. Inadequate polishing roughens surfaces and promotes microbial adhesion to titanium and zirconia. Sequential polishing to the finest-finish polishing tips minimizes bacterial adherence to abutment surfaces. Zirconia exhibited less bacterial adhesion than titanium.

A Critical Period for Robust Curriculum-Based Deep Reinforcement Learning of Sequential Action in a Robot Arm.

Many everyday activities are sequential in nature. That is, they can be seen as a sequence of subactions and sometimes subgoals. In the motor execution of sequential action, context effects are observed in which later subactions modulate the execution of earlier subactions (e.g., reaching for an overturned mug, people will optimize their grasp to achieve a comfortable end state). A trajectory (movement) adaptation of an often-used paradigm in the study of sequential action, the serial response time task, showed several context effects of which centering behavior is of special interest. Centering behavior refers to the tendency (or strategy) of subjects to move their arm or mouse cursor to a position equidistant to all stimuli in the absence of predictive information, thereby reducing movement time to all possible targets. In the current study, we investigated sequential action in a virtual robotic agent trained using proximal policy optimization, a state-of-the-art deep reinforcement learning algorithm. The agent was trained to reach for appearing targets, similar to a serial response time task given to humans. We found that agents were more likely to develop centering behavior similar to human subjects after curricularized learning. In our curriculum, we first rewarded agents for reaching targets before introducing a penalty for energy expenditure. When the penalty was applied with no curriculum, many agents failed to learn the task due to a lack of action space exploration, resulting in high variability of agents' performance. Our findings suggest that in virtual agents, similar to infants, early energetic exploration can promote robust later learning. This may have the same effect as infants' curiosity-based learning by which they shape their own curriculum. However, introducing new goals cannot wait too long, as there may be critical periods in development after which agents (as humans) cannot flexibly learn to incorporate new objectives. These lessons are making their way into machine learning and offer exciting new avenues for studying both human and machine learning of sequential action.

Evaluation of Dual-Cure Resin Cement Polymerization under Different Types and Thicknesses of Monolithic Zirconia.

PURPOSE: The aim of the present study was to investigate the effects of the type and thickness of the zirconia material on the microhardness of the underlying dual-cure resin cement. MATERIALS AND METHODS: Eight disk-shaped zirconia specimens with a 4-mm diameter and four varying thicknesses (0.5, 1.0, 1.5, and 2.0 mm) were fabricated from two different monolithic zirconia materials: posterior monolithic zirconia (Prettau) and anterior monolithic zirconia (Prettau Anterior). Dual-cure resin cement specimens with a 4-mm diameter and 5-mm height were prepared using Teflon cylinder molds and activated by light beneath the eight zirconia disks and without any zirconia disk for 20 s (n=12). A total of 108 specimens were embedded in acrylic. Vickers hardness of each specimen was measured at three different depths using a microhardness device with a 50-g load. All data were statistically evaluated using three-way ANOVA, one-way ANOVA, independent samples t-tests, and Bonferroni corrected post hoc tests (α=.05). RESULTS: Dual-cure resin cement's microhardness was significantly higher for the samples polymerized beneath anterior monolithic zirconia compared to posterior monolithic zirconia. The hardness decreased as the thickness increased for both types of zirconia; the latter was attributed to an attenuated curing efficiency. CONCLUSION: Microhardness of the dual-cure resin cement is influenced by both the type and the thickness of the monolithic zirconia restoration. Polymerization efficiency for resin cement cured under anterior monolithic zirconia may be superior to cured beneath posterior monolithic zirconia.

Extracellular Matrix Protein 1 Gene Mutation in Turkish Patients with Lipoid Proteinosis.

BACKGROUND: Lipoid proteinosis (LP) is a rare autosomal recessive genodermatosis characterized by mucocutaneous lesions and hoarseness of voice that develop in early childhood. LP is caused by mutation in the extracellular matrix protein 1 (ECM1) gene, which is located on 1q21.2. AIMS: This study aimed to present the profile of ECM1 gene mutations and to identify possible novel mutations specific to Turkey. MATERIALS AND METHODS: The ECM1 gene mutations of 19 LP patients from five families were evaluated using DNA isolated from peripheral blood samples. All ten exons in the ECM1 gene region were amplified by polymerase chain reaction (PCR). The PCR products were analyzed using a DNA sequencing analyzer. The results of DNA sequencing were analyzed with bioinformatics methods. RESULTS: of the 19 LP patients evaluated in our study, we detected defects in exon 6 (c.507delT, 658T>G), exon 9 (157C>T, 727C>T), and exon 10 (c.93_94delGCinsTT) of the ECM1 gene. CONCLUSIONS: Our results indicate that defects in exons 6, 9, and 10 of the ECM1 gene were responsible for LP in our country. The identification of these pathogenic mutations is valuable because it facilitates early diagnosis and genetic counseling.

Shear bond strength of luting cements to fixed superstructure metal surfaces under various seating forces.

PURPOSE: In this study, the shear bond strengths (SBS) of luting cements to fixed superstructure metal surfaces under various seating forces were investigated. MATERIALS AND METHODS: Seven different cements [Polycarboxylate (PCC), Glass-Ionomer (GIC), Zinc phospahate (ZPC), Self-adhesive resin (RXU), Resin (C&B), and Temporary cements ((RXT) and (TCS))] were bonded to a total number of 224 square blocks (5×5×3 mm) made of one pure metal [Titanium (CP Ti) and two metal alloys [Gold-Platinum (Au-Pt) and Cobalt-Chrome (Co-Cr)] under 10 N and 50 N seating forces. SBS values were determined and data were analyzed with 3-way ANOVA. Pairwise comparisons and interactions among groups were analyzed with Tukey's simultaneous confidence intervals. RESULTS: Overall mean scores indicated that Co-Cr showed the highest SBS values (1.96±0.4) (P<.00), while Au-Pt showed the lowest among all metals tested (1.57±0.4) (P<.00). Except for PCC/CP Ti, RXU/CP Ti, and GIC/Au-Pt factor level combinations (P<.00), the cements tested under 10 N seating force showed no significantly higher SBS values when compared to the values of those tested under 50 N seating force (P>.05). The PCC cement showed the highest mean SBS score (3.59±0.07) among all cements tested (P<.00), while the resin-based temporary luting cement RXT showed the lowest (0.39±0.07) (P<.00). CONCLUSION: Polycarboxylate cement provides reliable bonding performance to metal surfaces. Resin-based temporary luting cements can be used when retrievability is needed. GIC is not suitable for permanent cementation of fixed dental prostheses consisting of CP Ti or Au-Pt substructures.

Influences of Implant and Framework Materials on Stress Distribution: A Three-Dimensional Finite Element Analysis Study.

PURPOSE: The aim of this study was to analyze and compare the stress distribution patterns of different implant and restorative materials in the supporting tissue and implants. MATERIALS AND METHODS: Twelve different implant/bone models were created using SolidWorks 2015 software (SolidWorks Corp) and analyzed using the finite element method. Straumann Bone Level implants with zirconia abutments and single-piece Straumann PURE Ceramic implants (Institute Straumann) restored with lithium disilicate glass-ceramic and zirconia ceramic cement-retained crowns were evaluated. A 118.2-N load was applied to the coronal aspect of the buccal cusp at a 75.8-degree angle in relation to the occlusal plane. Principal stress values for cortical and trabecular bone and the equivalent von Mises stress values for implants and frameworks were calculated. RESULTS: Zirconia (ZrO2) implant models showed lower principal stress values than the commercially pure titanium (cpTi) and titanium-zirconium (TiZr) implant models in cortical bone. All models showed similar principal stress values in trabecular bone. Von Mises stress values at the cpTi and TiZr implants were similar; however, values observed of ZrO2 implants were higher. TiZr implants of 3.3 mm diameter showed similar strength to 4.1-mm-diameter cpTi implants. Both zirconia and lithium disilicate glass-ceramic frameworks transferred similar von Mises stress values in the supporting tissue of implant-supported prostheses. CONCLUSION: Narrow-diameter TiZr implants may be preferred for patients who have insufficient bone volume without bone augmentation procedures due to the material's enhanced biomechanical properties. ZrO2 implants may be a suitable alternative for esthetic regions. Further clinical studies are recommended to investigate the long-term performance of TiZr and ZrO2 implants.

Influence of monolithic lithium disilicate and zirconia thickness on polymerization efficiency of dual-cure resin cements.

OBJECTIVE: To evaluate the influence of anterior monolithic zirconia and lithium disilicate thickness on polymerization efficiency of dual-cure resin cements. MATERIALS AND METHODS: Twelve ceramic disks (4.0-mm diameter) with thicknesses of 0.5, 1, 1.5, 2, 2.5, and 3 mm were prepared from monolithic zirconia (Prettau® Anterior; n = 6) and lithium disilicate (IPS e.max® CAD HT; n = 6). Three dual-cure resin cements (Panavia F 2.0, DuoLink Universal™, and RelyX™ U200) were used for polymerization beneath ceramic disks. For each resin cement, 10 specimens were prepared by light curing under monolithic zirconia and lithium disilicate disks of each thickness. Vickers hardness measurements were conducted at four different measurement depths. Data were statistically analyzed using univariate four-, three-, two-, and one-way analysis of variance and independent samples t-tests. RESULTS: Microhardness of resin cements decreased significantly with increasing measurement depth and thickness of monolithic zirconia or lithium disilicate (P < .001). Cements polymerized under lithium disilicate showed higher microhardness values than did those polymerized under zirconia (P < .001). For both ceramics, Panavia F 2.0 exhibited the greatest microhardness, followed by DouLink Universal and RelyX™ U200 (P < .001). CONCLUSIONS: Different dual-cure resin cements may have different polymerization efficiencies, and the type and thickness of the overlying ceramic can influence polymerization. CLINICAL SIGNIFICANCE: The findings of this study suggest that an increase in the thickness of monolithic lithium disilicate or anterior monolithic zirconia restorations can significantly decrease the microhardness of the dual-cure resin cement polymerized beneath the restoration. Dual-cure resin cements can be used for the cementation of anterior monolithic zirconia restorations up to 2 mm thickness and for monolithic lithium disilicate restorations up to 2.5 mm thickness. However, for lithium disilicate restorations with a ≥2.5 mm thickness and zirconia restorations with a ≥2-mm thickness, different cementation approaches must be further studied, such as: extended light curing; the use of dual-cure resin cement with a higher self-curing component than the ones used in this study; or a self-cure resin cement.

Evaluation of five CAD/CAM materials by microstructural characterization and mechanical tests: a comparative in vitro study.

BACKGROUND: Polymer infiltrated ceramics and nano-ceramic resins are the new restorative materials which have been developed in order to enhance the adverse properties of glass-matrix ceramics and resin composites. The aim of the present in vitro study was to evaluate the characteristics of various CAD/CAM materials through mechanical, microstructural, and SEM analysis. METHODS: Five test groups (n = 22) were formed by using the indicated CAD/CAM blocks: VITA Enamic (VITA Zahnfabrik), Lava Ultimate (3 M ESPE), IPS e.max CAD (Ivoclar Vivadent), IPS Empress CAD (Ivoclar Vivadent), and VITA Mark II (VITA Zahnfabrik). Two specimens from each test group were used for XRD and EDS analysis. Remaining samples were divided into two subgroups (n = 10). One subgroup specimens were thermocycled (5 °C to 55 °C, 30s, 10,000 cycles) whereas the other were not. All of the specimens were evaluated in terms of flexural strength, Vickers hardness, and fracture toughness. Results were statistically analyzed using two-way ANOVA, one-way ANOVA, Tukey's HSD, and Student's t tests (α = .05). Fractured specimens were evaluated using SEM. RESULTS: The highest Vickers microhardness value was found for VITA Mark II (p < .001), however flexural strength and fracture toughness results were lowest conversely (p < .05). IPS e.max CAD was found to have the highest flexural strength (p < .001). Fracture toughness of IPS e.max CAD was also higher than other tested block materials (p < .001). Lava Ultimate and VITA Enamic's mechanical properties were affected negatively from thermocycling (p < .05). Microhardness, flexural strength, and fracture toughness values of Lava Ultimate and VITA Enamic were found to be similar to VITA Mark II and IPS Empress CAD groups. CONCLUSIONS: It should be realised that simulated aging process seem to affect ceramic-polymer composite materials more significantly than glass ceramics.

Effect of thickness and surface modifications on flexural strength of monolithic zirconia.

STATEMENT OF PROBLEM: A recommended minimum thickness for monolithic zirconia restorations has not been reported. Assessing a proper thickness that has the necessary load-bearing capacity but also conserves dental hard tissues is essential. PURPOSE: The purpose of this in vitro study was to evaluate the effect of thickness and surface modifications on monolithic zirconia after simulated masticatory stresses. MATERIAL AND METHODS: Monolithic zirconia disks (10 mm in diameter) were fabricated with 1.3 mm and 0.8 mm thicknesses. For each thickness, 21 disks were fabricated. The specimens of each group were further divided into 3 subgroups (n=7) according to the surface treatments applied: untreated (control), airborne-particle abrasion with 50-µm Al2O3 particles at a pressure of 400 kPa at 10 mm, and grinding with a diamond rotary instrument followed by polishing. The biaxial flexure strength was determined by using a piston-on-3-balls technique in a universal testing machine. Flexural loading was applied with a 1.4-mm diameter steel cylinder, centered on the disk, at a crosshead speed of 0.5 mm/min until fracture occurred. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were performed. The data were statistically analyzed with 2-way ANOVA, Tamhane T2, 1-way ANOVA, and Student t tests (α=.05). RESULTS: The 1.3-mm specimens had significantly higher flexural strength than the 0.8-mm specimens (P<.05). Airborne-particle abrasion significantly increased the flexural strength (P<.05). Grinding and polishing did not affect the flexural strength of the specimens (P>.05). CONCLUSIONS: The mean flexural strength of 0.8-mm and 1.3-mm thick monolithic zirconia was greater than reported masticatory forces. Airborne-particle abrasion increased the flexural strength of monolithic zirconia. Grinding did not affect flexural strength if subsequently polished.

Minimally Invasive Surgical Approach to Complicated Recurrent Pilonidal Sinus.

Pilonidal sinus is considered as a simple and frequently occurring disease localized at the sacrococcygeal area. However, at the intergluteal region, it can often turn into a chronic and complicated disease. In some cases, it can fistulize up to the gluteal region and appear at the secondary orifices. Minimally invasive surgical techniques are becoming widespread in recent years due to the increased experience and development of new instruments. Limited excision of the pilonidal sinus tract can be a better treatment option compared with large excisions in terms of recovery time and patient's comfort. This case study reports the single-phase surgical treatment of complicated and recurrent pilonidal sinus localized at the gluteal area, with minimal tissue loss and inflammation.

Evaluation of surface topography of zirconia ceramic after Er:YAG laser etching.

OBJECTIVE: The aim of this study is to evaluate the effect of Erbium: yttrium-aluminum-garnet (Er:YAG) laser with different pulse lengths on the surface roughness of zirconia ceramic and airborne particle abrasion. BACKGROUND DATA: Er:YAG laser treatment is expected to be an alternative surface treatment method for zirconia ceramics; however, the parameters and success of the application are not clear. METHODS: One hundred and forty zirconia discs (diameter, 10 mm; thickness, 1.2 mm) were prepared by a computer-aided design and computer-aided manufacturing (CAD/CAM) system according to the manufacturer's instructions. Specimens were divided into 14 groups (n=10). One group was left as polished control, one group was air-particle abraded with Al2O3 particles. For the laser treatment groups, laser irradiation was applied at three different pulse energy levels (100, 200, and 300 mJ) and for each energy level at four different pulse lengths; 50, 100, 300, and 600 µs. Surface roughness was evaluated with an optical profilometer and specimens were evaluated with scanning electron microscopy (SEM). RESULTS: Data was analyzed with one way ANOVA and Tukey multiple comparison tests (α=0.05). For the 100 and 200 mJ laser etching groups, 50 and 100 µs laser duration resulted in significantly higher surface roughness compared with air-particle abrasion (p<0.05). The difference among Ra values of 300 µs, 600 µs, and air-particle abrasion groups were not statistically significant (p>0.05). For the 300 mJ laser etching groups; there was no statistically significant difference among the Ra values of 50 µs, 100 µs, 300 µs, 600 µs, and air-particle abrasion groups (p>0.05). CONCLUSIONS: In order to increase surface roughness and promote better bonding to resin luting agents, Er:YAG laser etching may be an alternative to air-particle abrasion for zirconia ceramics. However, high levels of pulse energy and longer pulse length may have an adverse effect on micromechanical locking properties, because of a decrease in surface roughness.

Adhesion of 10-MDP containing resin cements to dentin with and without the etch-and-rinse technique.

PURPOSE: This study evaluated the adhesion of 10-MDP containing self-etch and self-adhesive resin cements to dentin with and without the use of etch-and-rinse technique. MATERIALS AND METHODS: Human third molars (N=180) were randomly divided into 6 groups (n=30 per group). Conventional (Panavia F2.0, Kuraray-PAN) and self-adhesive resin cements (Clearfil SA, Kuraray-CSA) were bonded to dentin surfaces either after application of 3-step etch-and-rinse (35% H3PO4 + ED Primer) or two-step self-etch adhesive resin (Clearfil SE Bond). Specimens were subjected to shear bond strength test using the universal testing machine (0.5 mm/min). The failure types were analyzed using a stereomicroscope and quality of hybrid layer was observed under a scanning electron microscope. The data (MPa) were analyzed using two-way ANOVA and Tukey's tests (α=.05). RESULTS: Overall, PAN adhesive cement showed significantly higher mean bond strength (12.5 ± 2.3 - 14.1 ± 2.4 MPa) than CSA cement (9.3 ± 1.4 - 13.9 ± 1.9 MPa) (P<.001). Adhesive failures were more frequent in CSA cement groups when used in conjunction with two-step self-adhesive (68%) or no adhesive at all (66%). Hybrid layer quality was inferior in CSA compared to PAN cement in all conditions. CONCLUSION: In clinical situations where bonding to dentin substrate is crucial, both conventional and self-adhesive resin cements based on 10-MDP can benefit from etch-and-rinse technique to achieve better quality of adhesion in the early clinical period.

Simultaneous Replacement of Maxillary Central Incisors with CEREC Biogeneric Reference Technique: A Case Report.

Biogeneric Reference Technique (BRT) of the CEREC 3D v.3.8 software is an effective technique for single anterior ceramic crowns because it provides computer-controlled match of the tooth form to the contralateral tooth. BRT also enables the fabrication of two or more anterior all-ceramic crowns simultaneously. This clinical report demonstrates the clinical application of BRT for designing and milling two central incisors in one appointment using a single optical impression. After completing the virtual design of the first central incisor, it was copied and a mirror image was created. The second central incisor was designed using this replicated image and therefore a computer-controlled symmetry was obtained. The crowns were milled from monolithic feldspathic ceramic blocks and adhesively luted with dual-cured resin cement following dentin conditioning. At the two-year follow-up appointment, the restorations were intact, no adverse effects were noted, and the resultant appearance was highly satisfactory for the patient. A step-by-step protocol is described from design to cementation of these restorations.

Evaluation of hardness and fracture toughness, coupled with microstructural analysis, of zirconia ceramics stored in environments with different pH values.

The aim of this study was to evaluate the effects of pH changes in the oral cavity on the mechanical properties of zirconia and feldspathic ceramics. Bilayered zirconia-feldspathic samples were prepared from three different commercial brands of Y-TZP blocks: Zirkonzahn, Cercon, and Everest. Samples were stored in artificial saliva with different pH values (3.5, 7.0, and 10.0) for 10 days at 37°C. Flexural strength, Vickers hardness, and fracture toughness were calculated after samples were subjected to biaxial flexure test. Microstructural analysis of the materials was also performed.Data were analyzed by one-way analysis of variance (ANOVA), and multiple comparisons were performed using Tukey's test (α=0.05). Acidic and alkaline environments adversely affected the mechanical properties of zirconia, resulting in material degradation, loss of stabilizer content, and increase in tetragonal-monoclinic phase transformation. Commercial dental zirconia blocks have varied mechanical properties, but they are generally susceptible to degradation when exposed to corrosive environments.

Influence of zirconia base and shade difference on polymerization efficiency of dual-cure resin cement.

PURPOSE: The aim of this study was to investigate the polymerization efficiency of dual-cured resin cement beneath different shades of zirconia-based feldsphathic ceramic restorations. MATERIALS AND METHODS: Five translucent zirconia (Zirkonzahn) discs (4.0-mm diameter, 1.2-mm height) were prepared. Feldsphathic ceramic (1.2 mm) (Noritake Cerabien Zr) in 5 shades (1M2, 2M2, 3M2, 4M2, 5M2) was applied on the zirconia discs. Twelve dual-cure resin cement specimens were prepared for each shade, using Panavia F 2.0 (Kuraray) in Teflon molds (4.0-mm diameter, 6.0-mm height), following the manufacturer's instructions. Light activation was performed through the zirconia-based ceramic discs for 20 seconds, using a quartz tungsten halogen curing device (Hilux 200) with irradiance of 600 mW/cm(2) . Immediately following light curing, specimens were stored for 24 hours in dry, light-proof containers. Vickers hardness measurements were conducted using a microhardness tester with a 50-g load applied for 15 seconds. The indentations were made in the cross sectional area at four depths, and the mean values were recorded as Vickers hardness number (VHN). Results were statistically analyzed with one-way ANOVA and Tukey HSD test (p < 0.05). RESULTS: A statistically significant decrease in VHN of the resin cement was noted with increasing depth and darkness of the shade (p < 0.05). CONCLUSION: Curing efficiency of dual-cure resin cement is mainly influenced by the lightness of the shades selected.

Clinical efficacy of the Vector system in excess cement removal during fixed prosthodontic treatment.

OBJECTIVE: To evaluate the clinical effectiveness of the Vector system (Durr Dental) in excess cement removal from subgingival margins during fixed prosthodontic treatment. METHOD AND MATERIALS: A total of 41 subjects, each in need of a minimum of 2 metal-ceramic crowns in different quadrants, took part in this study. Altogether, 156 abutment teeth were randomly assigned into 2 groups: In one group, excess cement was removed with the Vector system after cementation of provisional and permanent restorations, while in the other group, handheld instruments were used for this procedure. The clinical parameters Plaque Index (PI), Gingival Index (GI), and probing pocket depth (PPD) were recorded at baseline, at the same appointment after cementation of provisional restorations, 2 weeks later after cementation of permanent restorations, and 3 weeks after final cementation. RESULTS: Both the Vector system and the handheld instruments were able to reduce PPD and PI significantly at 2 and 5 weeks, but no significant differences could be demonstrated between the groups. Regarding GI, significant reductions were found at 2 and 5 weeks for the Vector group (P < .001), whereas for the handheld instrument group, the only significant difference could be demonstrated at 5 weeks (P = .001). Significant differences between the groups occurred at 2 weeks (P = .003) and 5 weeks (P = .002), with the Vector group having the greatest reduction in GI. CONCLUSION: Although similar reductions in Plaque Index and probing pocket depths were observed with both the Vector system and handheld instruments, the Vector system produced a significantly greater benefit in reducing Gingival Index.

Influence of different surface treatments on the short-term bond strength and durability between a zirconia post and a composite resin core material.

STATEMENT OF PROBLEM: Reliable bonding between zirconia posts and composite resin core materials is difficult to achieve because of the smooth surface texture and lack of silica content of zirconia posts. PURPOSE: The purpose of this study was to evaluate the effect of different surface treatments on the short-term bond strength and durability between a zirconia post and a composite resin core material. MATERIAL AND METHODS: Eighty zirconia posts were divided into 4 groups (n=20). Specimens received 1 of 4 different surface treatments: group AIRB, airborne-particle abrasion; group TSC-SIL, tribochemical silica coating (CoJet system) and silanization (ESPE Sil); group AIRB-BSIL, airborne-particle abrasion and MDP-containing primer (Clearfil SE Bond Primer)/silane coupling agent (Clearfil Porcelain Bond Activator) mixture application; and group TSC-BSIL, tribochemical silica coating and MDP-containing primer/silane coupling agent mixture application. Average surface roughness (Ra) of zirconia posts produced by airborne-particle abrasion or silica coating was measured using an optical profilometer. Composite resin core foundations (Build-it FR) were formed using transparent acrylic resin tubes (12mm in length and 7mm in diameter). Each group was further divided into 2 subgroups of 10 specimens and stored in distilled water at 37 degrees C, either for 24 hours or for 150 days with 37,500 thermal cycles between 5 degrees C and 55 degrees C, with a dwell time of 30 seconds. Following water storage, the specimens were sectioned perpendicular to the bonded interface into 2-mm-thick post-and-core specimens under water cooling. Push-out tests were performed with a universal testing machine at a crosshead speed of 0.5mm/min. Debonded post surfaces were examined with SEM. Data were analyzed with 1- and 2-way ANOVA and Tukey multiple comparison tests (alpha=0.05). RESULTS: No significant differences were detected between the Ra values of airborne-particle-abraded and silica-coated specimens (P=.781). The short-term mean bond strengths for group TSC-BSIL (27.1 +/- 3.2 MPa) and TSC-SIL (25.2 +/- 2.4 MPa) were statistically higher (P<.001) than AIRB-BSIL (23.3 +/- 2.2 MPa). The relatively high bond strengths for groups TSC-BSIL and TSC-SIL decreased significantly after 150 days of water storage to 13.5 +/- 1.6 and 11.8 +/- 1.2 MPa, respectively (P<.001). Durable bonding was obtained only in group AIRB-BSIL (21.8 +/- 2.7 MPa), which was also the only group demonstrating predominantly cohesive failures in the core material after long-term water storage. CONCLUSIONS: Data suggest that the short-term high bond strength obtained with a silane coupling agent or MPD-containing primer/silane coupling agent mixture to silica-coated zirconia posts was decreased with water storage and thermal cycling, whereas a durable bond could be obtained when an MPD-containing primer/silane coupling agent mixture was applied to the airborne-particle-abraded post surface.

Analytic view to concordance between electrocochleography and caloric test in Meniere's disease.

We aimed to investigate if there is a concordance between summation potential (SP)/action potential (AP) ratio and unilateral weakness in patients with definite-Meniere's disease. There were two groups, a group of unilateral definite-Meniere patients who received no treatment and another group of control subjects. Twenty-six patients were identified as complying with the defined criteria. Fifteen healthy subjects with no hearing and balance disorders were assigned to the control group. Arithmetic mean of the four-tone average of thresholds at 0.5, 1, 2, and 3 or 4 kHz, SP/AP ratio and degree of unilateral weakness were calculated. The number of patients was tabulated based on the presence of abnormal SP/AP ratio and unilateral weakness. Co-occurrence of unilateral weakness and elevated-SP/AP ratio was investigated with reference to the stage of the disease. A correlation was sought among pure-tone average, SP/AP ratio and degree of unilateral weakness in a pair-wise manner. Unilateral weakness and abnormal SP/AP ratio were identified in 53.8% and 38.4% of the patients, respectively. Co-occurrence of unilateral weakness and abnormal SP/AP ratio was observed in 34.6% of the patients. However, it was noticed that this co-occurrence gradually increased when the disease progressed. Mean SP/AP ratio also gradually increased as the stage progressed. Of pair-wise correlations among pure-tone average, SP/AP ratio and degree of unilateral weakness, a weak correlation (r = 0.383) was found only between SP/AP ratio and degree of unilateral weakness with marginal significance (P = 0.053). We concluded that co-occurrence of unilateral weakness and elevated SP/AP ratio increases when the disease progresses. This co-occurrence is less encountered in earlier stages. This difference might be resulted from a difference in distension capability of the endolymphatic space of the cochlea and the vestibule. Albeit weak, there was a correlation between mean SP/AP ratio and degree of unilateral weakness, which suggests that the disease parallelly disturbs the lateral semicircular or cochlear functions especially in advanced stages.

Effect of cochlear reserve on postoperative outcome in otosclerosis.

Patients with elevated bone conduction (BC) thresholds are not considered a good candidate for otosclerosis surgery. Sometimes, it might be difficult to decide to operate these patients considering relatively poor cochlear function. However, viewpoints may vary among otologists. This study was undertaken to compare hearing outcome following otosclerosis surgery in patients who had bone conduction (BC) thresholds >or= 30 dB, and to investigate whether BC thresholds >30 dB has a negative impact on hearing outcome. Medical records of 111 patients who had undergone otosclerosis surgery were reviewed. Of 111 patients, 83 had undergone stapedotomy, and 28 stapedectomy. The patients were grouped based on preoperative four-tone BC threshold. Eighty-seven patients had average BC threshold 30 dB, and constituted poor-cochlear reserve group. Pre- and postoperative air conduction (AC) and BC thresholds, air-bone (AB) gap, vocal audiometry results and amount of deterioration in BC were determined. Mean postoperative AB gap was almost the same in both groups (14 and 15 dB) (P > 0.05). Percentage of AB gap = 10 dB favored good-cochlear reserve group (41 vs 29%)(P > 0.05). Analysis of mean hearing gain was slightly in favor of good-cochlear reserve group (19 vs 15 dB) (P > 0.05). Better BC thresholds were obtained postoperatively in good-cochlear reserve group (P < 0.001). Deterioration > 10 dB in BC was observed in 5.7 and 12.5% of the patients with good- and poor-cochlear reserve, respectively (P > 0.05). Based on the results of this small sample-size study, even though BC threshold of 30 dB was not considered a negative factor for hearing gain, otosclerosis surgery might have detrimental effects on postoperative BC thresholds in patients who had BC thresholds >30 dB.

Shear bond strengths of two composite core materials after using all-in-one and single-bottle dentin adhesives.

PURPOSE: The purpose of this study was to compare the shear bond strengths of 2 composite core materials after using all-in-one and single-bottle dentin bonding materials. MATERIAL AND METHODS: The occlusal surfaces of 100 extracted, intact human third molars were ground to expose a flattened area of dentin and polished with 600-grit silicon carbide paper. Specimens were divided into 5 main groups (n= 20). Three all-in-one (AQ Bond, One-Up Bond, Xeno-CF Bond) and 2 single-bottle adhesives (Single Bond, One-Step Plus) were used. Each group was further divided into 2 subgroups. Ti-Core and Built-it F.R. core materials were applied using a translucent plastic ring (diameter: 3 mm, height: 5 mm). After storage in 37 degrees C water for 24 hours, shear bond strengths were measured using a Universal testing machine with a crosshead speed of 0.5 mm/min. Debonded dentin surfaces were examined with SEM. Two-way analysis of variance (ANOVA) and multiple comparison (Tukey) tests were used for statistical analysis of data. RESULTS: Two-way ANOVA revealed that the type of core material did not significantly influence the shear bond strength (p > 0.05), whereas there were significant differences in shear bond strength among the types of bonding agents (p < 0.0001). Shear bond strengths for single-bottle adhesive systems were significantly higher than those for all-in-one adhesive systems (p < 0.05). Furthermore, the interaction of these 2 parameters was not significant (p > 0.05). The fracture modes were predominantly adhesive for all-in-one adhesives and cohesive for single-bottle adhesives. CONCLUSION: Bonding of composite core materials with the newly developed all-in-one dentin adhesives produced lower shear bond strengths as compared with single-bottle adhesives.